Research on risk factors for IgE-mediated food allergy is limited. Given that food allergy is often the first manifestation of atopy, it is not only important to increase our knowledge of food allergy etiology and progression, but to identify risk factors for transient vs. persistent IgE-mediated food allergy, and ultimately use this information to develop interventions to prevent what amounts to an onset of the allergic march. The overall goal of this project is to use an existing birth cohort to explore potential risk factors for milk, egg, or peanut allergy, by age 24 months. Central to this proposal is the risk of food allergy associated with infant feeding practices, including age at introduction of solid or complementary foods and factors related to breastfeeding and duration of breastfeeding. We propose using data from the Wayne County Health, Environment &Atopy Longitudinal Study, or WHEALS birth cohort, established with NIAID funding in 2002. To this data, the proposed study will add (1) a panel of allergists who will make a determination of IgE-mediated food allergy by review of data from interviews with caregivers of infants in the cohort as well as available clinical data, including serum total and specific IgE measured from birth - 2 years and skin prick tests conducted at 2 years;(2) a medical chart review of the infant record, which will also be available to the panel of allergists for determination of IgE-FA;and (3) measurement of concentrations of transforming growth factor beta (TGF[unreadable]) and interleukin 10 (IL10) in mature breast milk. These activities are not included under funding of the current WHEALS grant, and neither food allergy nor food sensitization is an outcome for the aims of the previously funded WHEALS grant. Aim 1 of the proposed application is to estimate the prevalence of IgE-mediated food allergy at age 2 years. Aim 2 is to examine the relationship of infant feeding practices to prevalence of food allergy, adjusting for family history of allergy, exposure to tobacco smoke, indoor allergens and endotoxin measured in house dust. An exploratory Aim 3 is to use a case-control study to examine the relationship between prevalence of IgE-mediated food allergy and concentrations of transforming growth factor beta (TGF[unreadable]) and interleukin 10 (IL10) in mature breast milk. We will take advantage of the diversity in the WHEALS cohort to describe these relationships by race. The identification of modifiable risk factors for food allergy may lead to development of interventions that can delay progression of the allergic march, thereby reducing risk of asthma or other atopic diseases. This exploratory proposal should result in new paradigms of disease risk that can be applied to an increasingly diverse population, and represents a unique opportunity to gain a more comprehensive picture of how inherited and environmental factors can interact with behavior to influence risk of IgE-mediated allergy to milk, egg, and peanut. Research on risk factors for IgE-mediated food allergy is limited. It is important to increase our knowledge of the causes of food allergy and how it progresses. In this study, we will use an existing birth cohort to explore how infant feeding practices can influence development of IgE-mediated food allergy to egg, milk, or peanut. We will take advantage of the racial diversity in this study population to explore these relationships by race.